WO 2004/001867 describes a piezoelectric motor that provides a linear drive for an actuator. The motor uses a piezoelectric drive element that operates at high speed and with high precision. The piezoelectric motor described in WO 2004/001867 A1 comprises a stator that consists of two series-connected bending sections and a power transmission element which is mounted on the stator and transmits the bending action of the drive element to a sliding element. The drive element is aligned parallel to the sliding element and is made of an electrostrictive material, such as a piezoelectric material, or a magnetostrictive material. These kinds of materials change their shape when exposed to an electric voltage or magnetic field. The bending sections of the drive element are disposed symmetrical to the power transmission elements, the two bending sections performing a bending action that is similar to a traveling wave when an electric voltage or a magnetic field is applied. The wave-like movement is transmitted via the power transmission elements to the sliding element and in this way pushes the sliding element forwards incrementally.
The piezoelectric motor according to WO 2004/001867 A1 has proved useful in practice. The movement of the drive elements is transmitted via the power transmission elements to the sliding element in that the power transmission elements and the sliding element are in frictional contact. The electromechanical motor may be used as a regulating device that achieves a fast and precise lateral displacement of the sliding element and thus of an actuator connected to it. Piezoceramics have very short response times and thus very short operating times. One possible application for an electromechanical miniature motor of this type is in a central locking system for a motor vehicle, where the sliding element is used to actuate a lock cylinder.
WO 2004/001867 A1 describes the basic construction and functioning of the electromechanical motor, and reference is made to WO 2004/001867 A1 for an explanation of the functioning of the electromechanical motor. This document, however, does not explain how an electromechanical motor can be constructed in practice, in particular, it does not explain how the individual components are held and guided with respect to one another.
Other publications that deal with electromechanical motors of the kind described above include, for example, U.S. Pat. No. 6,437,485 B1 and U.S. Pat. No. 6,882,084 B2. Again these two documents do not reveal any tangible design for the electromechanical motor or any details as to how the individual components are held and guided with respect to one another.
Based on this prior art, one object of the invention is to provide a construction for an electromechanical motor that is not only compact and simple in design but also allows ease of assembly of the individual components.